In closed dry cleaning systems using chlorinated solvents, the solvent, during the filter cycle portion of the cleaning process, is conventionally passed by pressure through a filter assembly filter aid. Filters of the type referred to are disclosed in U.S. Pat. Nos. Carrier, 2,480,320, Hobson, 3,100,190 and Zehrback, 3,262,568. At the conclusion of a cleaning operation of predetermined length, the contaminated liquid solvent and the filter aid, dislodged from the filter elements and suspended in the liquid, are passed to a pot-type still where the solvent is distilled, separated from any water entrained in the distilled liquid, and returned to a storage tank for reuse. In the still, the toxic dust residue from the distilling process has, heretofore, been permitted to accumulate at the base of the still from which it is, at intervals, manually removed through a clean-out access door in the still. This removal operation is time consuming and, because of the toxic nature of the residue, extensive safety precautions for personnel engaged in the removal are necessary. The present invention is related to to an improved apparatus for removing the solid residue from a conventional dry cleaning solvent recovery still.
The apparatus of the present invention utilizes a free-running auger screw component moved in a reciprocating pattern over the base of the still to put the residue dust into a flushing stream of hot water introduced into the still and drained into the sewage system.
The filter assembly is composed of a tube header plate which accommodates a series of cylinders formed by perforated, rigid, stainless steel tubes. Drawn over each of the tubes is a nylon mesh bag which closely overlies the tubes and against which the filter powder is held by the pressure differential between the interior of the tubes and the space exterior to the tubes. The spacing of the tubes and their rigidity, contrasted with the deformable woven wire mesh tubes conventionally used, provide ease of disassembly for cleaning or repair.